Teen's murder conviction and sentence to be reconsidered more than two decades on

A teenager who murdered a truck driver with his own hammer will have her conviction and sentence reheard in court.

In 2003, Renee O'Brien was sentenced to life imprisonment for the 2002 murder of 60-year-old Waitara man Kenneth Pigott. She was just 14 at the time of the killing and was denied parole in 2014.

But Te Kāhui Tātari Ture / Criminal Cases Review Commission says it has obtained expert evidence that her "age, developmental stage and cognitive functioning may have affected her ability to understand and appreciate risk and form the intent required for murder".

"Te Kāhui also identified wider concerns affecting the fairness and reliability of the conviction," it said in a statement on Friday.

"This included O'Brien's ability to participate meaningfully in complex proceedings, uncertainty in the forensic pathology evidence, the late change of plea and evidence of a co-accused, party liability directions, and the use of O'Brien's police interview in her trial."

Acting deputy commissioner Professor Tracey McIntosh said their investigation posed "significant" questions.

"While no single issue necessarily determines the outcome, when considered together we concluded there were sufficient concerns for the Court of Appeal to consider her conviction again."

The commission also cited "significant developments in the law and understanding of adolescent neurological development and the sentencing of young people" since 2003, and that if sentenced today, it would be unlikely that she received a life sentence.

"Te Kāhui does not decide guilt or innocence, and a referral does not mean a conviction has been overturned," McIntosh said. "It means we have concluded that it is in the interests of justice for the case to be considered again by an appeal court."

O'Brien's lawyer Kerry Cook thanked Te Kāhui staff "for their diligent and thorough analysis of Renee’s case".

"Miscarriages of justice harm all society because they erode trust in the justice system and cause profound suffering. Fixing miscarriages is mandatory, not optional."